A hallmark of primary visual cortex is its organization into maps of visual space, orientation and ocular dominance. Despite remarkable advances in our ability to measure the structure of cortical maps and their mutual relationships, many important questions remain unanswered. How do these maps develop? Why are maps missing in some species? What role do maps play, if any, in cortical computation? The central goal of our research is to seek answers to these fundamental questions of cortical development, organization and function that have eluded us for decades. Our working hypothesis is that the blueprint for the formation of simple-cell receptive fields and orientation maps in primary visual cortex is encoded in the spatial layout of retinal ganglion cell (RGC) mosaics. To test the idea we will analyze the spatial statistics of RGC mosaics, reconstruct the retinal input to given orientation domains, and test the micro-organization of cortical maps. If the these ideas are confirmed, they can offer a definitive account for the origin of orientation maps in primary visua cortex and, more broadly, profoundly influence the way we conceive of cortical maps, their development and function.